Sweetening the land

Ellie Leary – Monuments for the Future Project Officer

Not all of the archaeology within the North York Moors is as ancient and enigmatic as the standing stones or rock art (see previous posts). Once a ubiquitous presence within the landscape, you can still stumble across the remains of a more industrial feature – lime kilns. These structures were part of an industry that has shaped and changed the landscape of the area from the extraction of the limestone from quarries to its end use as a building material and soil improver.

Over 400 lime kiln sites are recorded within the National Park’s Historic Environment Record, with the evidence coming mainly from historic maps, but also earthworks and standing remains. Only three of these kilns have the benefit of protected status as Scheduled Monuments, and in all cases they are included as part of a wider monument rather than in their own right. Another three have protected status as Grade II Listed Buildings.

Grade II Listed Building (1149198) - lime kiln, Hawnby (HER 5946). Copyright NYMNPA.

The use of lime has a long history in Britain dating back to at least the Roman period and over time it has had a wide range of practical uses from forming the base of plasters, mortar and concrete; as lime-wash for waterproofing walls and lightening interiors; in the bleaching of paper and preparing hides for tanning; as a disinfectant; and as a soil improver for agriculture.

During the Roman period it was used particularly for lime-mortar, plaster and lime wash; while during the mediaeval period the need for quantities of lime hugely increased with the construction of large stone-built buildings and bridges. From the 17th century onwards however the main use of lime has been in agriculture, with it being added to soil to improve acidic soils or as a top dressing to pasture to “sweeten” the land.

In most cases in order to turn raw limestone into a useable product it has to be fired in a kiln, creating a process called calcining where calcium carbonate is converted into calcium oxide. This process was both labour and fuel intensive and the trade was known as lime burning – those working at the kilns, were lime burners.

Most of the kilns known of within the North York Moors date to the 18th and 19th centuries, although earlier examples do exist. Excavations at Ayton Castle, for example, revealed a lime kiln dated to the 14th century, which may have produced lime mortar and cement for the construction of the castle’s tower house, the ruins of which still stand.  (This is one of the three kiln sites included within a wider Scheduled Monument – see above).

The earliest kilns were simple clamp kilns which consisted of a circular or rectangular hollow within which the limestone and fuel were layered, covered with clay or turf, and left to burn for a few days. Often clamp kilns leave little obvious trace, however the remaining protected kiln sites in this area (as mentioned above) include two clamp kilns built into the bank of a scheduled prehistoric cross dyke and another cut into the edge of a scheduled Bronze Age barrow – the actual kilns are all thought to be 18th or 19th century in date. Their remains can be seen as horse shoe shaped mounds of earth and stone rubble.

As the demand for lime increased kilns became more substantial in size although the transformation process remained the same. Kilns were generally circular or square stone structures, about 3m in height, with a bowl lined with sandstone or firebricks and at least one draw hole located at the bottom of the kiln. As the contents burnt through the lime was extracted through the draw holes at the bottom. Additional layers of stone and fuel could be added to the top if necessary, otherwise one-off firings were carried out as needed. A good example of this kind of kiln can be found at Old Byland where the remains of four lime kilns stand next to a road (see image below). They are located on the edge of a quarry to the south west of the village and some parts survive to 5m in height, with two of the kilns having the roof and flue surviving.

Old Byland roadside lime kilns (HER 2680). Copyright NYMNPA.

The end product removed from a kiln was called ‘lump lime’, ‘burnt lime’ or ‘quicklime’ and in order to convert this for use it has to be ‘slaked’ – a process involving adding water to cause a reaction which produces heat and steam. By then adding enough water, putty is produced, which, mixed with sand, produces a mortar. Over time this reverts back to calcium carbonate and hardens.  When used in agriculture the ‘lump lime’ was left in heaps, covered in earth and left to slake, eventually creating a powder that could be ploughed into the soil. Other methods were used too, including leaving the lime uncovered and occasionally turning to produce the same result.  ‘Lump lime’ is a volatile material and there were inherent dangers if it started to ‘slake’, producing heat, before it arrived at the final destination.  By the late 19th century, hydration plants were introduced that could grind the lime, sprinkle it with water, dry it and then bag it for transporting.

The location of kilns largely depends on the final use for the ‘quicklime’, so that if it were needed for building construction the kilns would most likely be located close to the building site. They could then either be dismantled and moved or left to decay once they were no longer needed.

Field kilns were sometimes built by farmers and land owning estates from the 17th century. Smaller kilns would have been built by farmers for occasional use to improve their land but estates often built larger kilns to serve the whole estate and wider area, providing a profitable source of income.

Another common location for kilns was close to or within limestone quarries. Many of these quarries are still obvious on the ground now as large excavated pits; historic mapping helps to identify the full extent of the quarries and the location of kilns. The 1893 Ordnance Survey map (below) shows Sour Ley Quarry near Helmsley with up to 20 lime kilns within the quarry.

Extract from 1:2,500 Ordnance Survey Map 1893

Easy access to transportation was also another consideration for the location – for fuel to be brought in and for the final product to taken away for sale.  Colonel Sir Joshua Crompton, 19th century owner of the Kepwick Estate on the western edge of the North York Moors, built a railway line in the early 1820s which carried limestone from a quarry on Kepwick Moor down to the lime kilns and stone yard to the west. Fuel for the kilns could be easily brought in and the final product taken away on the Thirsk to Yarm turnpike road (now the A19). With a very steep incline up to the quarry the railway used gravity; as the full wagons were sent down slope they pulled the empty ones up towards the quarry, whilst horses pulled the wagons along the flat plain to the west. The quarry and the start of the now dismantled railway line lie with the National Park boundary and the lime kilns themselves are a short distance outside the boundary and are protected as a Scheduled Monument.

Lime kiln north of Sinnington (HER 4981). Copyright NYMNPA.

As the demand for quicklime grew the process became industrialised, with new kilns designed with efficiency in mind as well as a higher quality lime product. As a result most of these smaller local kilns were abandoned by the 20th century, with some being dismantled and others left to decay, remaining in the landscape as a reminder of this chapter of industry.

To keep up to date with the latest National Park response to Covid-19 – see here.

Leaving a mark

Graham Lee – Archaeological Officer

‘Rock Art’ in archaeological terms consists of markings made by human beings on exposed stone surfaces. The earliest rock art from around the world has been dated to between 10,000-50,000 years ago, whereas within the North York Moors National Park the rock art appears to belong to the time span between the Late Neolithic and the Early Bronze Age periods, approximately 3,200-1,500 BC. Motifs created by carving were made into the rock surface using a sharp tool with a ‘pecking’ technique and can range in complexity from simple cups and grooves to quite elaborate patterns. The cup marks (sometimes enclosed by an outer groove – then called cup and ring marks, Fig. 1) tend to be shallow, semi-spherical hollows between c.3-12 cms across, with the depth generally proportional to the diameter, depending on the amount of surface erosion that may have occurred.

Cup and ring marks - copyright NYMNPA

Fig. 1 (above): Cup and ring marks on a heavily marked rock on Fylingdales Moor. Two roughly pecked rings can be seen coming together in the centre-right of the image.

The main concentration of prehistoric rock art within the North York Moors National Park lies within Fylingdales Moor which was affected by a wildfire in 2003. Survey after the fire has significantly increased the known resource (as previously recorded by the local rock art experts and enthusiasts) by over 60% – from approximately 120 sites to over 200. Given that the wildfire affected just over half (c.250 out of c.480 hectares) of this surviving area of coastal moorland (north-east of the A171), and that the latter in total only forms a small proportion of the overall Fylingdales moorland block, the full extent of the distribution of carved rocks in the area probably still remains to be discovered. Some of the carvings appear so fresh that it is thought that they are likely to have become completely buried in prehistory, to then be revealed anew by the wildfire. Such a site is probably that represented by a site on Brow Moor (Figs. 2-3), which was discovered under burnt vegetation in October 2003 and provides an example of excellent preservation. The individual peck-marks which form the decorative markings in the stone can still clearly be seen.

Cup and ring marks - copyright NYMNPA

Fig. 2 (above) and Fig. 3 (below): A remarkably ‘fresh’ carving on Brow Moor, as discovered in 2003 and after a few years regenerative growth. Note the level of surviving detail, including the individual peck-marks.

Cup and ring marks - copyright Blaise Vyner

The heat of the wild fire resulted in damage to some of the rocks by causing the surface of the stone to crack and flake away (known as spalling, Fig. 4). In addition to this, the chemistry of the stone may also have been irreversibly altered, affecting the cements that hold the rock particles together. This can influence the subsequent absorption of moisture which, due to freeze/thaw action during winter, can cause further spalling. The loss of covering material, such as the layers of roots and peat which had grown over the rock surfaces, also appears to have left the carved rocks more vulnerable to disturbance and erosion.

Wildfire burn - cup and ring marks - copyright Blaise Vyner

Fig. 4 (above): Spalling damage to a rock on Fylingdales Moor, caused by heat generated from the wildfire. Clearly this can lead to irreversible damage to any surviving rock art.

All the known examples of rock art on Fylingdales Moor appear to be carved into the local middle Jurassic Dogger series sandstone. Many of these rocks are likely to have been exposed to the elements – to weathering and biological attack – for well over 4,000 years. During this period of time it is likely that other wildfire events will have occurred, together with fires set deliberately for land management purposes. The latter will have increased within the last 150-200 years as part of grouse moor heather management  but in recent decades management for wildlife, rather than grouse shooting, has become the priority on this estate. Controlled burning is designed to cause minimal heat and damage, however it may still – depending on the chemistry of the rocks in question, and the nature of the ‘burn’ – cause some negative impacts to the prehistoric carvings.

In order to tackle the potential future loss of detail to these sites, a range of recording techniques and practices have been employed. The Fylingdale Moor sites have all been recorded by local experts and enthusiasts (see Brown and Chappell 2005), but in particular a group of 26 carved rocks were chosen for monitoring in order to provide a baseline record of condition against which to assess erosion and damage in future years. These have all been recorded by stereoscopic photography by Historic England, with a further group of 12 laser scanned at 0.5mm resolution.

Accurate location is also an essential part of site management, due to the difficulties of relocating sites on large areas of open (often rather ‘featureless’) moorland where long heather or other dense vegetation has developed. In the last few decades practical management has tended to become more mechanical with the use of rotating chain flail cutters attached to tractors, both to create fire breaks and to harvest the heather, which is sometimes baled and used e.g. as an environmental filter. It is consequently of particular importance to know the precise location of all the rock art panels to ensure that potential damage does not accidentally occur.

Many of the examples of rock art on Fylingdales Moor are protected as Scheduled Monuments. As part of our work under Monuments for the Future, and previously under the Monument Management Scheme, we send volunteers out to make regular monitoring visits to check on monument condition – however it is not always easy to find the correct rocks! In some areas bracken has been a problem, not only damaging other archaeological features, such as Bronze Age burial mounds, which may be associated with the rock art but obscuring the rocks making them difficult to find and therefore vulnerable to accidental damage. Over the last few years we have worked with Natural England and the managers of Fylingdales Moor to ensure that appropriate bracken control has kept some of these features clear of vegetation.

Further Reading
Brown, P. M. and Chappell, G. 2005 Prehistoric Rock Art in the North York Moors, Tempus, Stroud
Vyner, B. E. 2007a Fylingdales Wildfire and Archaeology, North York Moors National Park.

Moor mounds

Ellie Leary – Monuments for the Future Project Officer

Welcome to the latest instalment of our blog celebrating the archaeology of the North York Moors. As the newest member of the Monuments for the Future Team I should probably take this opportunity to introduce myself as a new Project Officer. I started out in professional archaeology 20 years ago, working in a variety of roles, mostly in the field, although the last few years have been spent providing archaeological advice to local authorities. Previously I mainly knew the North York Moors through holidays, but now I can really immerse myself in this beautiful landscape and its wonderful archaeology.

Since moving here I’ve spent every spare moment pouring over OS Explorer maps of the area and planning trips. If you’ve ever done this you might have seen the words ‘tumulus’, ‘tumuli’ or ‘cairn’ frequently dotted across them. Marked in the spidery Gothic script used to mark archaeological remains, a tumulus or cairn refers to a mound (either of earth or stone respectively). Many of those marked will be Bronze Age burial mounds known as round barrows or round cairns. Another way to spot these archaeological features on your map is by names, such as Cock Howe or Three Howes – Howe is an Old Norse word for a mound or barrow.

Round barrows or cairns typically date to the Bronze Age, with the large majority constructed between 4000 to 3500 years ago (2000 – 1500 BCE). They can vary quite widely in size, and come in a few different types, but the most common type you are likely to encounter will have a mound shaped like an inverted bowl, constructed from earth and/or stone which cover single or multiple burials (inhumations or cremations), with the mound sometimes originally surrounded by a circular ditch.

These evocative monuments would have been clearly visible in their day and are found in prominent positions. Such clearly visible features would have acted as commemorative and territorial landmarks, but also had significant social and cosmological meaning. They may also have been way markers, tracing out ancient routeways.

This visibility also means that these monuments have attracted attention through the following millennia, drawing people to them. We can see this in their re-use, for example the medieval and later cross at Ana Cross on Spaunton Moor below.

Ana Cross on round barrow with erosion repair carried out under Monument Management Scheme. Copyright NYMNPA.

Here antiquarian digging in later centuries has left distinctive indentations on the summit and sides, and then there are the modern walkers cairns. Our modern curiosity frequently results in inadvertent erosion, as numerous feet make their way onto the summit along the same route.

Very occasionally we have the opportunity to look inside a round barrow. Excavations in 2011 through the round barrow within Boltby Scar hillfort showed that the mound had been constructed in several phases, one of which included the ring of stone rubble visible below.

Inside Boltby Scar Hillfort round barrow, 2011. Copyright NYMNPA.

Many barrows are mapped and marked as tumuli on the OS Explorer, but this really only scratches the surface of the actual number found within the North York Moors. Round barrows make up a substantial proportion (the majority in fact) of the Scheduled Monuments in the National Park, with a total of 541 of the area’s monuments including at least one round barrow or round cairn (64%of the total). A further 680 unscheduled barrows are recorded within the North York Moors Historic Environment Record. Some of the unscheduled barrows are visible earthworks, but many are only indicated by very slight rises in the ground or as cropmarks spotted in aerial photographs.

Current issues affecting round barrows and cairns include erosion, bracken or scrub growth and walkers cairns. A previous blog post highlighted the issue of walkers cairns and the work we were doing under the Monument Management Scheme (MMS). Now Monuments for the Future  is continuing this work, as well as helping to preserve some of the more eroded or overgrown barrows, and monitoring their ongoing condition.

Cock Howe round barrow on Bilsdale West Moor with erosion repair carried out under Monument Management Scheme. Copyright NYMNPA.

We will also be carrying out research into the survival of below ground remains of round barrows under arable cultivation. Some barrows may have been under the plough for centuries so there may be very little to see on the surface now, but burials and other features may survive – our challenge is to find out what lies under the plough soil and determine the best techniques to record remains and preserve them for the future.

With so many round barrows and cairns across the North York Moors, you are never too far away from one. Look out for mounds on the horizon as you travel across the moorland, or you might come across one at closer quarters. Try finding some of these:

Fortifying the landscape

Emma Trevarthen – former Monuments for the Future Officer
Emma now works for Historic England carrying out aerial surveys of archaeological sites, so she’ll still be keeping an eye on the moors but this time from the skies

Prehistoric hillforts and promontory forts of the North York Moors

Eight prehistoric fortified sites have been recorded within the North York Moors National Park. These monuments command some of the highest points in the Moors and the ramparts of some can still be clearly seen, their defensive nature apparent.

The earthwork ramparts at Round Hill hillfort. Copyright NYMNPA.

The earthwork ramparts at Round Hill hillfort

With the exception of the hillfort at Round Hill at Westerdale (a mutivallate hillfort with two or more lines of earthwork defences), all are described as Promontory Forts and are located for the most part at the western and northern edges of the Cleveland Hills. Their existence, and that of the long linear earthworks they are associated with, suggests a period of consolidation of settlement and social organisation in the Iron Age, roughly 2,500 years ago.

As the names suggest, hill forts and promontory forts utilise natural topographic features to create defended spaces which would have housed people, animals and various industries. They would have been clearly visible to the surrounding countryside suggesting not only a desire to fortify and protect but also to project the high status of the residents. The defences would have consisted of a series of imposing banks and deep ditches with a break for a well-defended gated entrance. Within the fortified area there were likely to be domestic dwellings, shelters for livestock and storage areas for food and weaponry.

Recent archaeological excavation at Boltby Scar suggests that this site may have been in use from the Late Bronze Age, roughly 3,000 years ago. It is likely to be contemporary with Roulston Scar, the largest Iron Age fort in the north of England, which is immediately to its south with Lake Gormire almost equidistant between the two.

Reconstruction drawing of the defensive banks and ditches at Boltby Scar promontory fort. Copyright NYMNPA.

Reconstruction drawing of the defensive banks and ditches at Boltby Scar promontory fort

Although outside the boundary of the National Park, it is worth noting another promontory fort, Eston Nab, which has also been dated to the Late Bronze Age and with Roulston Scar, Boltby Scar and Knolls End, forms a band of forts from the coast around the western high ground of the Cleveland Hills, overlooking the Tees Valley in the north and the Vale of York to the south.

Place names

The word ‘Scar’ is likely to derive from a Norse word, ‘skera’, meaning a cliff or rocky outcrop with a steep face. It is an element that occurs often in place names throughout the North York Moors, often combined with other descriptive terms, such as in Hagg Scar Wood and Whitestone Scar, or joined with a local place name such as at Boltby Scar.

‘Nab’ has a similar meaning, describing a rocky promontory or outcrop. In the North York Moors there are a number of ‘Nab’ place names including Penny Nab, Highcliffe Nab, lots of Nab Ends and even a Nab Scar.

Folklore

Although the Giants of the North York Moors are credited with a number of landscaping events, there does not appear to have been a connection made between them and the creation of any of the Iron Age forts recorded on the Moors. Nor are there any definite links with horses, white or otherwise, even though Boltby Scar lies adjacent to a historic horse racing track, and Roulston Scar overshadows the (Victorian) Kilburn White Horse.  Themes associated with hillforts in other parts of the country such as buried treasure and slumbering dragons are also absent.

However, the Devil does get a name check at Roulston Scar in the form of the Devil’s Parlour, a natural fissure or cave in the cliff face just below the fort site where apparently the Devil appears at midnight. Also the Devil’s Leap is the space jumped by the Devil when he tried to show off by leaping from Roulston Scar to Hood Hill; a rock from the Scar bearing his footprint is said to reside at the foot of the hill.

The Devil’s Leap: from Roulston Scar to Hood Hill. Copyright NYMNPA.

The Devil’s Leap: from Roulston Scar (on the left) to Hood Hill (on the right)

Any other folk tales or curious place names associated with the forts of the North York Moors would be gratefully received. Remnants of cultural history are always worth collecting.

Access

Of the monuments within the National Park, Knoll’s End (Live Moor), Boltby Scar, Horn Ridge (Farndale), Baysdale and Hasty Bank are accessible via public footpaths, bridleways and areas of open access land; the last, Hasty Bank, is part of the Wainstones Walk

Roulston Scar lies within the grounds of the Yorkshire Gliding Club, a public footpath follows its western edge and forms part of the White Horse Walk

A public bridleway traces the circumference of Birk Bank, near Old Byland.
Round Hill is on private land and landowner permission would be needed to visit it.

Eston Nab can be accessed via public footpaths and bridleways.

Further Reading

Boltby Scar: http://www.landscaperesearchcentre.org/html/boltby_scar.html

Roulston Scar: https://research.historicengland.org.uk/Report.aspx?i=15487

1988 Vyner, B The Hill-fort at Eston Nab, Eston, Cleveland Archaeological Journal 145 p60-98

Beneath another pile of stones

Mags Waughman – NPA Monument Management Scheme Officer

Archaeology often uncovers the unexpected, but it usually relates to activities which are hundreds if not thousands of years old, but last week we found something which is much more recent.

As part of our work under the Historic England funded Monument Management Scheme (Phase 3), we have been trying to improve the visibility and condition of a number of Bronze Age burial mounds (usually dating to around 1700-2000 BC) which have been obscured in recent years by the addition of modern cairns on top of them. Walkers who may be unaware of the ancient burial mound beneath a pile of stones are sometimes tempted to pull stones out of the prehistoric monument to add to the modern cairn on top and this causes damage the ancient fabric of the monument. Many of these burial mounds are protected in law as Scheduled Monuments so it is especially important that we try to stop the damage and conserve what is left of them. Dismantling modern cairns from the top of these monuments can remove the temptation to extract stones for cairn building and restores the profile of the monument to something which is more recognisable as a Bronze Age burial mound.

One such burial mound on Gisborough Moor is getting an improvement makeover at the moment. This is quite a low and not very imposing mound which is distinguished by having a rough kerb of low stones set into the ground around its perimeter and a larger earthfast stone – a stone slab set vertically into the ground – on its north side. Small standing stones like this are believed to be prehistoric and in this case to have been part of the structure of the burial mound.

We organised an archaeological survey of the monument last autumn (carried out by Solstice Heritage) to be followed up, once the snows had gone, with the removal of the modern stones. During the survey work we were intrigued by a lump of concrete which was visible, poking out from the bottom of the cairn. We were wondering how someone had managed to lift it onto the monument and in particular how we would be able to remove it. Come last week, a team of our volunteers and apprentices guided by Chris Scott from Solstice Heritage took down the modern cairn, taking care to inspect the stones for any signs of prehistoric decoration. None were found, but underneath the modern accumulation of stones, the lump of concrete turned out to be much more interesting than we had originally thought.

Copyright Solstice HeritageAbove: Modern cairn on top of the burial mound: the standing stone is at the left hand side and you can just see the concrete block next to it.

Marked in the top of the concrete were the initials ‘CS’ and ‘JP’  with the date 11/11/1943 and in the centre was a deep and narrow cylindrical hole. We think that the initials are those of the people who cast the block and that it may have been intended to take either a flagpole or a communications mast. We know that parts of the surrounding moorland were used during World War II as a bombing decoy site  – an arrangement of controlled fires which would have been lit during an air raid to  draw enemy bombers away from Middlesbrough – so the presence of concrete dating from this time is not surprising. The 11 November date suggests that it may have been installed as part of an Armistice Day commemoration: perhaps the servicemen manning the decoy site held a ceremony of remembrance for the dead of the previous world war.

Copyright Solstice Heritage

Above: Cast slab of WWII concrete – possibly a flagpole base

Although modern additions to prehistoric monuments often look out of place, in this case the World War II concrete slab is part of the history of this site and so it will be left in place to tell its own story. As for the Bronze Age burial mound – now that the modern cairn has gone, it is much easier to see the shape of the mound and the standing stone set within it as another visible part of the heritage of the North York Moors landscape and its much earlier past.

Copyright Solstice Heritage

Above: Monument after removal of the modern cairn – the standing stone with the concrete block in front of it is at the far side of the mound in the centre of the picture and some of the kerb stones can be seen in the foreground

We will be keeping an eye on the monument over the coming months to see whether the vegetation is regenerating on the bare ground left by the removal of the modern cairn, and if necessary we will return later in the year to give it a helping hand. We will also watch out for the re-appearance of new cairns, but expect that this will be less likely to happen now that there are no loose stones on the surface  –  we would hope that visitors will respect both the prehistoric burial mound and the relic of our more recent past by not building any new cairns on the monument.

Copyright Solstice Heritage

Above: The stoical team after a day’s work in the March wind